Impact pulverization of particulate matter has long been conventionally effected by impaction techniques in apparatus generally delineated as "hammer mills". Such "hammer mills", while of widely varying construction and nomenclature, normally employ a plurality of rapidly advancing hammer members or other particle impacting members peripherally mounted on a high speed rotor with cooperating means to introduce the solid material to be comminuted into the path of such rapidly moving hammer members. Such solid material, usually in the form of large size particulates is conventionally fed into the hammer path by gravity or by conveyors or, in some instances, by an air stream and generally in a direction normal to the tangent to the path of displacement motion of the rotating hammer faces in order to obtain maximum velocity differentials and/or maximum energy transfer between the moving hammer faces and the material to be comminuted.
While such hammer mills are widely used for the comminution of materials, they are not particularly well adapted to efficiently effect the selective reduction of minor fractions of oversized particulates entrained in a gas borne stream of preformed or precomminuted particulate matter. While the presence of minor fractions of oversized particulate material will normally be found, in varying degree, in the output gas stream from conventional hammer mills, the presence of such oversize particulates is particularly troublesome in the processing of carbon black since such oversized particulates are there normally in the nature of undesired inpurities therein, such as scale, brick or other reaction vessel materials and/or coke particulates, and their presence results in certain problems when the carbon black product is later used in diverse physical and chemical processes.